Parents make tradeoffs between care for offspring and themselves. Such a tradeoff should be reduced in biparental species, when both parents provide parental care. However, in some biparental species, the contribution of one sex varies greatly over time or between pairs. How this variation in parental care influences self-maintenance rhythms is often unclear. In this study, we used continuous video recording to investigate the daily rhythms of sleep and feather preening in incubating females of the Northern Lapwing (Vanellus vanellus), a wader with a highly variable male contribution to incubation. We found that the female’s sleep frequency peaked after sunrise and before sunset but was low in the middle of the day and especially during the night. In contrast, preening frequency followed a 24-h rhythm and peaked in the middle of the day. Taken together, incubating females rarely slept or preened during the night, when the predation pressure was highest. Moreover, the sleeping and preening rhythms were modulated by the male contribution to incubation. Females that were paired with more contributing males showed a stronger sleep rhythm but also a weaker preening rhythm. If more incubating males also invest more in nest guarding and deterring daylight predators, their females may afford more sleep on the nest during the day and preen more when they are off the nest. Whether the lack of sleep in females paired with less caregiving males has fitness consequences awaits future investigation.

父母在照顾后代和照顾自己之间做出权衡。在双亲物种中，当父母双方都提供父母照顾时，这种权衡应该减少。然而，在一些双亲物种中，一个性别的贡献随时间或在成对之间变化很大。父母照顾的这种变化如何影响自我维持节奏通常不清楚。在这项研究中，我们使用连续视频记录来研究孵化的北麦地鸡（Vanellus vanellus)，一种对孵化的雄性贡献高度可变的涉禽。我们发现雌性的睡眠频率在日出后和日落前达到峰值，但在中午时分较低，尤其是在夜间。相比之下，梳理频率遵循 24 小时的节奏，并在一天中间达到峰值。总之，孵化的雌性在捕食压力最高的夜间很少睡觉或打扮。此外，睡眠和整理节律受到雄性对孵化的影响。与更有贡献的男性配对的女性表现出更强的睡眠节奏，但也表现出较弱的梳理节奏。如果更多孵化中的雄性在保护巢穴和阻止日光掠食者方面投入更多，那么它们的雌性白天可能会在巢中睡得更多，而在离开巢穴时会打扮得更漂亮。